Sheet metal receptacle and method of making



9, 1966 M. KAUFMAN 3,265,022

SHEET METAL RECEPTACLE AND METHOD OF MAKING Original Filed Sept. 7, 1961 2 $heets-Sheet l INVENTOR. Y lfolelezs Kql/FM/M/ Aug. 9, 1966 Original Filed Sept. '7, 1961 M. KAUFMAN 3,265,022

SHEET METAL RECEPTACLE AND METHOD OF MAKING 2 Sheets-Sheet 2 7 INVENTOR.

M RI lKWFM/W United States Patent This invention relates to improvements in the manufacture and production of metal receptacles, such, for example, as folded type rectangular bread loaf baking pans formed from a single blank of sheet metal or the like in which a certain amount of fullness or excess of material generated at the upright corners of the pan is commonly taken care of by folding the excess material flat against a wall of the pan to create corner folds or laps of twoply thickness. This application is a division of an earlier filed co-pending application entitled Sheet Metal Receptacle and Method of Making, Serial No. 136,545, filed September 7, 1961, and now Patent No. 3,219,229, issued on November 23, 1965 It is a primary object of this invention to so construct a folded type pan of the character indicated in which the two plies of each corner fold and the pan wall overlapped by said plies are bonded together by a fused joint throughout a strip-like area extending along the line of bend between each ply of the corner fold and the pan wall of which it forms a continuation whereby the corners of the pan coincident with said line of bend are given added rigidity and consequent protection against distortion under stress of impacts encountered along said corners while said pans are in actual service.

It is also an object of this invention to provide a pan of this type wherein the strip-like area representing the fused joint, and marginal portions of the pan Walls adjacent the upright boundaries of said joint are merged along inwardly facing concavely curved lines having their axes of curvature lengthwise of the fused joint whereby the interior of the pan is free of pockets in which foreign matter might otherwise collect and interfere with maintenance of sanitary conditions within the pan.

With the above and other objects in view, as will be apparent, this invention consists in the construction, combination and arrangement of parts, all as hereinafter more fully described, claimed and illustrated in the accompanying drawing, wherein:

FIG. 1 is a plan view of a sheet metal blank for production of a pan in accordance with this invention, while said blank is in a fiat state.

FIG. 2 is an enlarged top perspective view of the blank shown in FIG. 1 illustrating the same as a partially completed folded pan and showing the surplus material at the corners arranged in two ply folds against one of the pan walls of which the innermost ply of said folds forms a continuation.

FIG. 3 is an enlarged fragmentary sectional view taken along line 33 of FIG. 2 and showing forming dies in a position preparatory to acting on the pan corner area to deform the same in accordance with the dotted line portion.

FIG. 4 is a similar view showing the corner of the pan in a deformed state under action of the dies in preparation fof the production of a fused joint between the plies of the corner folds and the pan wall overlapped thereby.

FIG. 5 is an enlarged section illustrating the method of initially fusing the plies of the corner fold and the pan wall overlapped thereby.

FIG. 6 is a similar view illustrating the method of extending the fused area of the plies of the corner fold with a subsequent welding step and simultaneously smoothening and concavely curving the inner surface of the pan corner along the fused joint.

FIG. 7 is a similar view showing a section through the fused joint resulting from the process illustrated in FIG. 6.

FIG. 8 is a fragmentary bottom perspective view of the pan as it appears subsequent to the formation of an integral outwardly turned closed reinforcing bead along the upper edges thereof.

FIG. 9 is a section showing a magnified view of the zone between the plies of the corner fold and the pan wall overlapped thereby.

FIG. 10 is a top perspective view of the pan in a final state of production.

FIG. 11 is a diagrammatic view of the interior of the pan shown in FIG. 10.

Referring to the drawing, FIG. 1 shows a blank of sheet metal of suitable contour for forming a folded pan in accordance with this invention. As initial steps in the transformation of the blank in accordance with the process of this invention, the blank 10 is bent along fold lines indicated by dotted lines in FIG. 1 to produce a pan having a flat bottom 10 of rectangular plan and upwardly bent side and end walls 11 and 12 respectively. The excess material developed at the corners of the blank 10 is preferably arranged in two ply folds 13 against the outer surface of the pan wall of which the innermost ply of said fold 13 is a continuation.

Subsequent to the operation of initially bending the walls 11 and 12 into the position shown in FIG. 2, the blank 10 is acted on by dies 14 and 14a along the line of bend between the folds 13 and the walls 11 and 12 to deform the corner portion of the pan. Under action of the dies 14 and 14a, as shown in FIG. 4, a marginal area of the plies of the fold 13 and a portion of the pan wall 12 overlapped thereby along one side of the bend between the pan wall 12 and the innermost ply and a marginal area of the pan wall 10 :along the opposite side of' said bend between pan wall 12 and the innermost ply of the corner lap 13 are flattened and thereby brought into coplanar relation along parallel planes extending obliquely to the pan wall surfaces at the boundaries of said flattened area.

After the corner areas of the pan have been thus flattened, said corner area is next subjected to the action of welding electrodes as shown in FIG. 5, wherein an inner electrode 15 of convexly curved contour is applied to the inner surface of the pan corner area along the bend between the innermost ply of the corner fold 13 and the wall 12 while an outer electrode 16 of fiat contour is applied to the outer surface of said corner area'directly opposite said inner electrode 15. While the corner area is thus subjected to heavy localized electric current and mechanical pressure of said electrodes 15 and,16, the inner and outer ply of the corner fold 13 and the pan Wall 12 of which the inner ply forms a continuation are integrally fused together along a strip-like area or seam as indicated at 17 in FIG. 5, and extending the full length of the line of bend between the corner folds 13 and the pan walls 11 and 12 as shown in FIG. 10.

While thus joined by the seam 17, the corner area is again subjected to welding temperature under pressure of the electrodes 15 and 16 as shown in FIG. 6 with the pressure applied along a line of force BB slightly angular to the line of force AA as applied in the initial welding step shown in FIG. 5 whereby the zone of fusion is spread and of gradually reduced depth in the direction opposite to that direction in which the plies of the corner fold 13 extend away from the seam 17. Simultaneously with the second welding step, the electrodes 15 and 16 are operative to compress and arch the fused joint and to obtain a merger of the surfaces of the pan walls adjoining said fused joint along inwardly facing concavely curved lines about an axis of curvature extending lengthwise of said fused joint.

The pan is thereupon subjected to action of suitable dies effective to produce a spherical contour at the junction between the bottom wall 11 of the pan and the lower limits of the pan walls 12 and 13 adjoining the corners defined by said walls as shown in FIG. 8. Accordingly the interior of the pan is concavely rounded along the junction of said walls 12 and 13 and the junction of the bottom wall 11 and said walls 12 and 13 at the lower end of .the junction of said walls 12 and 13 so as to eliminate pockets or crevices in which foreign matter would otherwise collect and render the interior of the pan unsanitary.

A wire 18 encircling the upper limits of the pan is enclosed by an outwardly curled closed bead along the upper edge of the walls 12 and 13 which provides additional reinforcement at the mouth of the pan.

The fused joint thus effected along the corners of a pan unit in accordance with this invention is of such rigidity and durability by reason of the welded connection between the two plies of corner fold material and the pan Wall overlapped thereby that the pan blank may be formed of relatively light gauge metal while maintaining resistance to stresses encountered in the use of the pans under normal service conditions.

The pan when thus in a finished state, as shown in FIG. 10, is subsequently cleaned and resurfaced with a protective coating of tin or other suitable material and thus placed in readiness for use as a pan for the baking of bread and the like.

While this invention has been described in connection with a pan of specific shape and design, the features and advantages theerof are of utility in pans of a variety of multi-sided sizes and shapes.

I claim:

1. The method of making a sheet metal pan which comprises bending a sheet metal blank along lines to form a bottom wall of rectangular plan and side walls extending upwardly from said bottom wall, joining said side walls by doubling up material thereof to form two ply corner folds and bending each corner fold against the outer surface of one of the side Walls of which said fold forms a continuation, applying an inner electrode to the inner surface of an area of the pan along the junction line between said side walls while applying an outer electrode to the outer surface of the pan directly opposite said inner electrode, subjecting said area to heavy localized electric current and mechanical pressure of said electrode along a first fixed direction of force to integrally fuse each ply of the corner fold at said junction line to the other ply of said corner fold and to the side wall of the pan overlapped thereby along a zone extending the full length of said junction line, and thereafter subjecting said area to heavy localized electric current and mechanical pressure of said electrodes along a second fixed direction of force in such angular relation to the first fixed direction of force as to spread and gradually reduce the thickness of said zone of fusion in the direction opposite to that direction which said plies of the corner fold extend from said junction line.

2. The method according to claim 1 wherein said area of the pan along said junction line and facing said electrodes is flattened prior to the step of initially subjecting said area to pressure of said electrodes along said first direction of force, and compressing and arching said flattened area along concavely curved lines facing inwardly of the pan and about an axis of curvature extending lengthwise of said junction line while subjecting said area to pressure of said electrodes in said second welding step.

References Cited by the Examiner UNITED STATES PATENTS 1,153,313 9/1915 Katzinger 113l20 1,438,698 12/l922 Debs 113-120 1,462,640 7/1923 Hoffman l13l20 CHARLES W. LANHAM, Primary Examiner.

R. D. GREFE, Assistant Examiner. 

1. THE METHOD OF MAKING A SHEET METAL PAN WHICH COMPRISES BENDING A SHEET METAL BLANK ALONG LINES TO FORM A BOTTOM WALL OF RECTANGULAR PLAN AND SIDE WALLS EXTENDING UPWARDLY FROM SAID BOTTOM WALL, JOINING SAID SIDE WALLS BY DOUBLING UP MATERIAL THEREOF TO FORM TWO PLY CORNER FOLDS AND BENDING EACH CORNER FOLD AGAINST THE OUTER SURFACE OF ONE OF THE SIDE WALLS OF WHICH SAID FOLD FORMS A CONTINUATION, APPLYING AN INNER ELECTRODE TO THE INNER SURFACE OF AN AREA OF THE PAN ALONG THE JUNCTION LINE BETWEEN SAID SIDE WALLS WHILE APPLYING AN OUTER ELECTRODE TO THE OUTER SURFACE OF THE PAN DIRECTLY OPPOSITE SAID INNER ELECTRODE, SUBJECTING SAID AREA TO HEAVY LOCALIZED ELECTRIC CURRENT AND MECHANICAL PRESSURE OF SAID ELECTRODE ALONG A FIRST FIXED DIRECTION OF FORCE TO INTEGRALLY FUSE EACH PLY OF THE CORNER FOLD AT SAID JUNCTION LINE TO THE OTHER PLY OF SAID CORNER FOLD AND TO THE SIDE WALL OF THE PAN OVERLAPPED THEREBY ALONG A ZONE EXTENDING THE FULL LENGTH OF SAID JUNCTION LINE, AND THEREAFTER SUBJECTING SAID AREA TO HEAVY LOCALIZED ELECTRIC CURRENT AND MECHANICAL PRESSURE OF SAID ELECTRODES ALONG A SECOND FIXED DIRECTION OF FORCE IN SUCH ANGULAR RELATION TO THE FIRST FIXED DIRECTION OF FORCE AS TO SPREAD AND GRADUALLY REDUCE THE THICKNESS OF SAID ZONE OF FUSION IN THE DIRECTION OPPOSITE TO THAT DIRECTION WHICH SAID PLIES OF THE CORNER FOLD EXTEND FROM SAID JUNCTION LINE. 